Firing mechanism



March 10, 1931- G. M. M CANN FIRING MECHANISM 2 Sheets-Sheet 1 Filed May 26. 1928 Mama March 10, 1931.

G. M. M CANN FIRING MECHANISM Filed May 26, 1928 2 Sheets-Sheet 2 i 1 .4552252 T :TH

Bu ge MQM E-Em Patented Mar. 19, 1931 treats GEORGE M. MCCANN, 035 NEW CASTLE, DELAWARE FIBXTDIG IIIECHANISM Application filed May 26, 1928.

Serial No. 280,855.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1928; 370 G. 757) The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The subject of this invention is a firing mechanism particularly designed as an improvement on the mechanism shown in Patent No. 710,124 of September 30, 1902.

In the type of mechanism disclosed in the patent an actuator, a firing pin and a spring are arranged so that the firing movement of the actuator energizes the spring and then releases the firing pin to be driven home by the spring. When the force thus applied to the actuator is removed the rearward action of the spring being directly applied to the actuator through a leverage which is greater than the indirect application thereto through the firing pin of the forward action of the spring produces retraction of the mechanism to the cocked position and retention in this position. The scar which is provided for holding the firing pin during compression of the spring is in the form of a leaf spring and is under a longitudinal strain when struck a transverse blow by the actuator to disengage it from the firing pm. This action has resulted in frequent breaking of the sear. A 30 leaf spring sear of sufficient strength to resist breaking will be deficient in elasticity.

In remedying this condition i have formed a sear of a comparatively heavy non-elastic body and have pivoted it on the fulcrum of the actuator so that it becomes a part of the self contained firing mechanism.

With the foregoing and other objects in view, my invention resides in the novel arrangement and combination of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without departing from the spirit of the invention.

A practical embodiment of the invention is illustrated in the accompanying drawings, wherein: 5.5a, 1 is a longitudinal sectional view through the firing mechanism showing the parts in the cool-red position;

Fig. 2 is a similar view showing the parts in the fired position;

Fig. 3 is a view in rear elevation of a sliding breech block equipped with the firing mechanism;

Fig. a is a sectional view substantially on the line 1-4 of Fig. 1;

Fig. 5 is a reduced sectional view on the line l'lof Fig. 1 with parts removed;

Figs. 6 and 7 are, respectively, views in plan and side elevation of the sear; and

Fig. 8 is a plan view of the firing pin.

Referring to the drawings by numerals of reference:

In carrying out the invention the breech block 5 is formed with a bore 6 which is closed at the face of the block by a plug 7 having a central aperture 8. A casing 9 containing a firing mechanism is inserted into the bore from the rear of the block and retained by means of a bayonet joint 10. The firing mechanism which is housed within the casing comprises a firing pin 11, a sleeve 12 slidable on the stem 13 of the pin and a spring 14 confined between a collar 15 on the pin and the base 16 of the sleeve. Extension of the firing pin and sleeve is limited by a lug 17 formed on the upper rear end of the pin and projecting into the path of movement of the sleeve.

Mounted transversely both in the breech block 5 and casing 9 is a shaft 18 to which is fixed an external actuating lever 19 and 8 also an arm 20 placed in line with the firing pin and bifurcated to embrace the stem thereof. The arm is in engagement through the forward face of its extremities 21 with the rearface of the sleeve 12 and it is also in engagement through an intermediate portion 22 whose rear face may bear against lugs 23 on the firing pin with such force. In this manner the rearward and forward actions of the spring are transmitted to the arm 95 with different leverages.

The casing 9 is formed with a longitudinally disposed groove 24: in which is placed a heavy rigid sear 25 formed with spaced bearings 26 embracing the arm 20 and jourended on the shaft 18. The hearing which is on the side from which the shaft 18 is in troduced is of a dian'ieter to permit the pasof the squared portion Which c r- 5 rice the arm 20. The forward portion oi the sear is formed with the usual detent 28 for engaging the collar of the firi pin and with a cam which is en ased b 7 the 1 L r t} L sic-eve LO depress th sear. ihe intermediate 10 portion of the sear is provided on its outer side with a stud which fits into a heiical sear spring 31 set in a recess 3; in the casch r is considered rncted to with :an'sverse strains oted is arranger novel manner in the casing containing the firing mechanism.

1 claim 1. A iJSGQCl block formed with a bore, casing securabie in the bore and having iongitudinaliy disposed groove, a iuicrumed ac-- tuator, a spring confined between the firing pin and actuator, disposed in the groove in the casing and having spaced bearings embracing a portion of the actuator and mount ed on the fulcrum thereof and a sear spring carried by the casing,

r breech block formed with a bore, a

casi securabie in the here, a fulcrunied ac- .15 tuator, a spring confined between the firing pin and actuator, a sear disposed in the cashaving spaced bearings embracing a portion of the actuator and mounted on the fulcrum thereof and a spring carried by 40 the casing.

3. In a firing mechanism, av casing, a firing pit in. the casing, a tulcruined actuator, a

spring confined'between the pin and actuator,

a seer disposed in the casing and having bearings mounted on the fulcrum of the actuator and a scar spring carried by the casing. 7

4. A breech block formec'i with bore, a

casing insertabie Wholly Within the bore and 59 securable therein, a firing pin in the casing,

mechanism in luding an arm tulcrumed in the casing for moving the pin to cocked and fired position, sear in the casing pivotally mounted on the fulcrum of the arm, and a sear spring.

5. A breech block formed with a bore, a casing insertabie Wholly Within the bore and securabie therein, and a firing mechanism including a fulcruined arm within the casing. to 6. In a firing mechanism, a fining pin,

mechanism including a fulcruined arm for moving the firing pin to cooked and fired position, and a scar pivotaiiy mounted on the fulcrum or" the arm.

enonen M. MoCANN, 

